Patients frequently require traction in treating orthopedic problems. Traction is normally applied by attaching a harness to the appropriate portion of the patient's body and connecting that harness to a weight. The force of traction produced by the weight is applied to the harness by connecting the harness to the weight with a cord that is run over a pulley positioned near the foot of the patient's bed. The vertical force produced by the weight is thereby converted to substantially horizontal force pulling on the harness.
Patients usually are not in traction continuously. It is frequently necessary or desirable to relieve traction for such purposes as having the patient change his position in bed, having the patient get out of bed, or simply relieving the force of traction for a period of time so that the patient can be more comfortable. When the patient needs to relieve the traction force it has been necessary to get assistance. A nurse or other attendant is called to lift the weight simply because the patient is unable to do it himself.
Patient's attempts at self-help to relieve the weight of traction can be difficult and even dangerous. Although some patients may be able to raise the weight by simply pulling on the cord strung over the pulley, it is difficult for the patient to hold the cord tightly while simultaneously changing position or while disengaging the cord from the harness. If the weight should fall it could produce a surge of force caused by the momentum of the weight reaching the end of the cord which would be uncomfortable or dangerous. It would also be difficult to lower the weight gently enough so that the traction force is reapplied gradually and without danger. Some patients are unable to lift the weight because they ar not strong enough or because the cord cannot be reached.